Fuel tank inspection/maintenance recommendations

[gene8084]

The tank in my 1974 Thunderbird, Formula 180 is under the deck (I?m guessing 30 gallons). I can access the sending unit and the shut-off through the 6" Deck plate, but that's about it.

I'm not sure what the material is, could be aluminum. There is about 5-6" of insulation foam between the deck and the tank so I can't see beyond the small area below the deck plate.

I'm a little concerned that fuel flow may be inhibited since I'm having problems getting the engine to run, idle or otherwise. Recently changed the fuel water seperator, new fuel pump, and rebuilt the carburetor.

I've emptied the bowl and it slowly fills while choked and cranking, but I'm not sure how quickly the bowl should fill. It kind of gurgles in and almost looks aerated until it fills and settles down.

Should I drain the fuel level down 10-15 gallons, pull the sending unit and have a look with a small flashlight and dentist mirror?

1. If so, what should I look for? top of the tank scaling?
2. Condition of the pickup?
3. Is there a diagram / picture somewhere of what a typical pickup from this time period should look like?
4. Other?

Thank you.

Gene

 

[Don S]

Re: Fuel tank inspection/maintenance recommendations

Moving to Boat Topics and Questions (not engine topics) .

 

[Solittle]

Re: Fuel tank inspection/maintenance recommendations

A couple of theings Gene. First does it pass the smell test which would indicate a leak somewhere? Next what does the fuel look like if you dump the contents of the filter/water seperator into a glass jar - - looking for crud? Next bypass your builtin tank and try to draw from a six gallon tank - - that will tell you if the problem is with the builtin tank. Last replace a section of the fuel line with a clear line and check for bubbles (air) as it pumps.

You didn't tell us what kind of power you have - - outboard or I/O. There are some other checks that apply depending on the power plant.

 

[SpinnerBait_Nut]

Re: Fuel tank inspection/maintenance recommendations

Solittle, look in his sig and it tells you.
302 Ford powered.

 

[gene8084]

Re: Fuel tank inspection/maintenance recommendations

Solittle, look in his sig and it tells you.
302 Ford powered.

That's right. Thanks.

The fuel in the bowl is clear. I replaced the fuel/water seperator a few weeks back as part of htis overhaul, but I can certainly remove it and inspect the contents.

The fuel line appears to be in really good shape. I think the last owner replaced the hoses and resealed all the fittings with teflon tape. The hoses look fresh and the teflon tape is bright white (new looking).

Configuration: Ford 302, built-in fuel tank, about 3-4 feet of hose, fuel bowl, fuel/water separator, fuel pump (new), Holley 2 barrel.

I like your idea of trying an external fuel can...I'll have to pick one up and give that a try before delving into draining the built-in.

Thanks.

 

[gene8084]

Re: Fuel tank inspection/maintenance recommendations

Reporting back.

I tried an external fuel source. It didn't resolve my starting problem. It turned out to be carburetor adjustment, but at least I was able to rule out the fuel tank.

I still wanted to confirm the tanks condition.
1. passed the smell test, but there was a loose fitting on the intake side of the pump. Only showed up when I primed the line (pressure) which it normally would not have. However, it may have been sucking some air.
2. There was some water in the new fuel water separator.
3. Blew out the line, back to the tank, no obvious obstruction/clogging.
4. Comparing the fuel in the bowl from the external source to the fuel in the main tank, the gas in the tank was orange.
4. I decided to drain the main tank. (good thing) It looks like the bottom 1/3 was old, cloudy, and had some particulate.
5. Pulled the sending unit to have a look and to pump from the lower corner of the tank that I couldn't get through the pickup. (This gas was even worse). This stuff would clealy mix and move around when running and clog my freshly rebuilt carb.
6. Tank looked clean inside, but I never could actually see the pickup. I think it's welded. I just could not see enough to risk trying to turn it and cracking a weld.
7. Gravity draining of the tank with a line through the hull drain plug was unobstructed (a good test).
7. Reinstalling the sending unit was a nightmare. There were two threaded collars inside the tank that dropped in when I removed the 5 sending unit bolts. I don't know if this is typical, but what a bad design. (happy to descibe how I reinstalled if anyone's interested, thank God for wire ties)

All clean now and ready for another 33 years!

 

[Chris1956]

Re: Fuel tank inspection/maintenance recommendations

Gene, A fuel tank of that vintage might be steel. If so, you might like to watch it for rustinduced leaks. You can check it's construction with a magnet.